Pippa Middleton gave birth Monday afternoon to her first baby, a boy, adding another grandchild to the Middleton clan and a first first-cousin for Prince George, Princess Charlotte and baby Prince Louis of Cambridge.

The birth was confirmed Tuesday morning by Middleton's representative in London, Jo Milloy.

"He was born Monday (October 15th) at 1:58 p.m., weighing 8 (pounds) and 9 (ounces)," the representative told USA TODAY. "Everyone is delighted and Mother and baby are doing well."

James Matthews and Pippa Middleton attend the wedding of Princess Eugenie of York and Jack Brooksbank at St George's Chapel in Windsor Castle on Oct. 12, 2018.(Photo: Samir Hussein/Pool/WireImage)

The younger sister of the former Kate Middleton, now Duchess Kate of Cambridge, Pippa, 35, had her baby at St. Mary's Hospital in London (where the royal children were born), with husband James Matthews by her side.

This is Pippa's first child, and the fourth grandchild for her parents, Carole and Michael Middleton, who also have a son, James, 31, who is not married.

Pippa Middleton wore a printed Anna Mason midi dress with a drop waist, ruffled tiers and a tie around her baby bump when she attended Wimbledon with husband James Matthews on July 13, 2018 in London.(Photo: Karwai Tang/WireImage)

For the little Cambridge royals, including future king Prince George, now 5, the new baby is their first cousin; so far, they have four second cousins, the children of their father, Prince William's, first cousins, Peter Phillips and Zara Phillips Tyndall.

The royal kids can also expect a new first cousin soon: Uncle Prince Harry, 34, and Duchess Meghan, 37, announced Monday they are expecting their first child in the spring.

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Though she was not an official bridesmaid, Duchess Kate repaid her sister with the child-wrangling services Pippa rendered at the royal wedding in 2011. It's only fair: two of the kids in the wedding party were hers. Kirsty Wigglesworth, AP

Spencer Matthews, left, gestures as he stands with James Middleton, right, and Donna Air at the entrance of St Mark's Church in Englefield, England, ahead of the wedding of his brother James Matthews to Pippa Middleton. Kirsty Wigglesworth, AP

A gigantic glass marquee has been built in Pippa Middleton's parents' backyard for the evening reception. Curtains were installed ahead of the wedding to ensure privacy for the guests. Neil P. Mockford, Getty Images

With many royals, including Duchess Kate, Prince William and little Prince George and Princess Charlotte on the guest list, not just anyone will be able to access the church grounds. Neil P. Mockford, Getty Images

Pippa herself revealed her condition in her monthly fitness column for Waitrose Weekend magazine, in a piece about exercising during pregnancy. (Pippa is as health-conscious and sporty as her sister.)

But she's been luckier than her sister, who suffered crippling bouts of acute morning sickness in the early stages of her three pregnancies. Among other things, that forced Kensington Palace to announce her pregnancies earlier than usual.

"I was lucky to pass the 12-week scan without suffering from morning sickness," Pippa wrote. "That meant I was able to carry (on) as normal and continue my sports."

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Pippa Middleton Matthews, sister of Duchess Kate of Cambridge, was in the final days of her pregnancy at the wedding of Princess Eugenie of York and Jack Brooksbank at St George's Chapel, Windsor Castle on Oct. 12, 2018. Three days later, her first child, a boy, was born at St. Mary's Hospital in London. Adrian Dennis/WPA Pool/Getty Images

Pippa attended Princess Eugenie's royal wedding with her husband, James Matthews. Pippa wore an evergreen, high-necked maxi dress by Emilia Wickstead dress with a matching wide-brimmed hat to finish off her look. Samir Hussein/Pool/WireImage

For her final Wimbledon look of 2018, Pippa Middleton wore a printed, multi-tiered maxi dress by Anna Mason and tied her hair back in a low ponytail with French braids on the side. Karwai Tang/Getty Images

Happy birthday, Pippa! Pippa Middleton Matthews turns 35 on Sept. 6, 2018. it will be a year unlike any other for Duchess Kate's younger sister, who is expecting her first child. To celebrate, take a look back on her best style looks, like the blue dress and hat she wore to the christening of nephew Prince Louis, held July 9, 2018 in the Chapel Royal at St James's Palace. Dominic Lipinski/Pool/AP

Joined by husband James Matthews, Pippa Middleton Matthews wore a baby-blue ensemble to her nephew's christening: a pleated, button-down dress with a dropped waist and high white collar by Alessandra Rich, plus matching fascinator and pumps. Prince Louis of Cambridge was christened at the Chapel Royal, St James's Palace, London on July 9, 2018. DOMINIC LIPINSKI, AFP/Getty Images

Pippa Middleton and husband James Matthews arrive for the wedding of Prince Harry and Meghan Markle at St George's Chapel, Windsor Castle on May 19, 2018. She wore a loose-fitting, mint-green dress with floral detailing by The Fold. Chris Jackson/ Getty Images

Pippa Middleton, the sister of Duchess Kate of Cambridge, was among the first to visit her sister's new baby, Prince Louis, on April 24, 2018, at Kensington Palace in London, one day after he was born. Jack Taylor, Getty Images

Pippa Middleton, in a white tiered floral dress, attended the final day of Wimbledon, this time with her mother and brother, for the men's singles final on July 16, 2017 in London. Karwai Tang, WireImage

Pippa Middleton and new husband James Matthews, back from their honeymoon, are pictured for the first time together at Wimbledon. On July 14, 2017, they were at Centre Court for the men's single semifinal match in London. She wore a white dress by Étoile Isabel Marant, plus a white fedora with a dark ribbon on the brim. Alastair Grant, AP

Now that her honeymoon with hubby James Matthews is over, Pippa Middleton is back in the U.K. for Wimbledon. She attended day three of the event wearing a soft pink, lacey dress by Self Portrait on July 5 in London. Karwai Tang, WireImage

Pippa was accompanied by brother James Middleton, who sat in the look centre court royal box. Duchess Kate's younger sister topped off her look with large sunglasses and a low ponytail. Clive Brunskill, Getty Images

Pippa and new hubby James Matthews arrived at Rose Bay Wharf by sea plane in Sydney on May 31, 2017 for their honeymoon.
Pippa and Matthews, who married on May 20, 2017, are visiting Sydney on their honeymoon. SAEED KHAN, AFP/Getty Images

Pippa Middleton arriving for the ParaSnowBall 2017 fundraiser held at The Hurlingham Club on May 4, 2017 in London. The younger sister of Duchess Kate of Cambridge is to marry hedge-fund millionaire James Matthews on May 20 near her parents' Bucklebury home 50 miles from London. Ricky Vigil, M/GC Images

That's Pippa on the left, in a brown coat and snappy fedora on Jan. 8, 2017, at Sandringham, where she accompanied her parents, sister, brother and fiance James Matthews to Sunday services at St. Mary Magdalene Church with the royal family led by the queen. Stephen Pond, Getty Images

Pippa Middleton and her fiance James Matthews together in a picture? That's almost as rare as Prince Harry with his new girlfriend Meghan Markle. But Pippa and James turned out for Christmas Day services at St Mark's Church in Englefield, the little village church where they will marry in May, near her parents Bucklebury estate 50 miles west of London. The couple stand in the church door, with her father Michael Middleton on the right. ANDREW MATTHEWS, AFP/Getty Images

She's engaged and wearing her ring. Pippa went for a run outside her London home, July 20, 2016, a day after she and her hedge fund manager boyfriend, James Matthews, announced their engagement and plans to marry in 2017. Philip Toscano, AP

Pippa and boyfriend-now-fiance James Matthews attended day nine of Wimbledon, marking their first public appearance as a couple. The hedge fund manager, 40, and Pippa, 32, have been friends for years and previously dated back in 2013. Karwai Tang, WireImage

Wimbledon 2016 opened June 27 and naturally tennis fan Pippa Middleton was there, along with brother James Middleton. She wore a flowered frock by British brand Suzannah, similar to other dresses Pippa has worn to Wimbledon in recent years. See Pippa's outfits over the years. Karwai Tang, WireImage

When Prince William got engaged to his longtime girlfriend Kate Middleton in 2010, few Americans knew much about her, let alone her younger sister, Philippa, or Pippa. But that's all changed for the young woman who's become a princess of the paparazzi. Now that Pippa has turned 30, on Sept. 6, take a look back at some of the pictures that made her almost as famous as her sis the royal duchess.
One of our first glimpses of her was in February 2011, shortly before the royal wedding, when she attended the wedding of her friend, the daughter of the Duke of Northumberland, at a castle in northern England. Chris Jackson Getty Images

Pippa's shapely style gets its first presentation at the Northumberland wedding, when she arrives at the church in a satiny black coat through which peeps a red lace dress. But her topper was tops, a bright red-and-black skull-cap-style fascinator perched on the side of her head. Paul Ellis AFP/Getty Images

The shot that launched a thousand paparazzi. Pippa follows Kate and father Michael into the Abbey, showing off her shapely rear in a sleek McQueen gown. So impressed were so many that Pippa's bottom even got its own instant Twitter account. Martin Meissner AP

After the wedding, Pippa appeared on the balcony of Buckingham Palace with members of both families, including best man Prince Harry. Their friendly demeanor during the wedding helped excite feverish speculation about these two eventually becoming a couple, but it was just a fantasy. WPA Pool Getty Images

Pippa and the Middletons departed the Goring Hotel the day after the wedding. Her outfit of a royal blue blazer and white jeans is typical of her chic look even in casual attire. Ian Gavan Getty Images

After the royal wedding, the paparazzi couldn't get enough of Pippa, snapping her constantly in London and elsewhere in the months following. It helps that she's always smiling and almost never takes a bad picture. Here she is on the street in Kensington on May 19, 2011. Notice the casual chic again. Neil Mockford FilmMagic

More tennis shots: Pippa cheers during match between Rafael Nadal of Spain and Radek Stepanek of Czech Republic at the AEGON Championships at Queens Club on June 9, 2011 in London. Clive Brunskill Getty Images

As with all celebs, Pippa turns up at a fashion show with other celebs. She was in the front row with Peaches Geldof and Rosario Dawson to her right, at the Temperley spring/summer show for London Fashion Week at the British Museum on Sept. 19, 2011. Tim Whitby Getty Images

Pippa and James and the rest of the Middletons board a boat and join the flotilla of hundreds of boats celebrating the queen's Diamond Jubilee during the Thames River Pageant on June 3, 2012. Notice the demure outfit she wore for that cold, rainy, very royal day. Paul Ellis AFP/Getty Images

You can't be a real celeb unless you walk an occasional red carpet. Here Pippa struts her stuff for the UK premiere of the film 'Shadow Dancer' at a theater in London on Aug. 13, 2012. Lefteris Pitarakis AP

Pippa is said to like visiting New York, especially for tennis. Here she watches Czech Tomas Berdych play against Switzerland's Roger Federer during their 2012 US Open men's singles quarterfinal match at the US Open in New York on Sept. 5, 2012. Emmanuel Dunand AFP/Getty Images

Pippa's new boyfriend of some months is banker/stockbroker Nico Jackson, son of a middle-class family that runs a ski-and-sportswear shop in a small town in Kent. Are they secretly engaged, as some reports put it? Stay tuned. Here they leave a new London club, Mr Fogg's, on May 21, 2013. Ben Pruchnie FilmMagic

A few days later, Pippa sports a peplum outfit and another quirky fascinator for a wedding of another daughter of the Duke of Northumberland, at his castle in Alnwick, England, on June 22, 2013. Scott Heppell AP

Who's more famous? Pippa sits next to former U.S. Secretary of State Condoleezza Rice in the box at center court for the men's first round match on the first day of Wimbledon 2013, on June 24, just a few days after the Northumberland wedding. Adrian Dennis AFP/Getty Images

Pippa and James and their parents get seats in the royal box during a gala at Buckingham Palace celebrating the queen's 1953 coronation, on July 11, 2013.
It's another sign that Pippa and the Middletons are now part of the royal entourage at major public events. What's next for her? No surprise if wedding bells chime soon. WPA Pool Getty Images

There's always another wedding among the young-aristo crowd in the U.K., and Pippa is often invited. On Sept. 14, she attended nuptials of James Meade and Lady Laura Marsham in King's Lynn, England. Boyfriend Nico Jackson wasn't there but Prince William and Prince Harry, close friends of the groom, both were there. But not Duchess Kate nor baby Prince George. As usual at an English wedding, the hats stand out. Pippa wore a fitted dress of teal blue with a lace overlay and a perky oval hat in the same color, decorated with peacock feathers. Danny E. Martindale FilmMagic

And there are other family celebrations to shine at. Pippa and James were among the elite few present at the christening of nephew Prince George in the Chapel Royal of St. James's Palace on Oct. 23. She stood out in a custom-made coat-and-dress ensemble by British designer Suzannah Crabb, with a complementary pill-box hat perched on the front side of her head. The coat was cream wool trapeze-style with pale pink trim, and the dress was blush lace, plus suede high-heeled pumps. John Stillwell, PA wire/epa

Once again, the engagement-is-imminent stories are appearing, after Pippa and banker boyfriend Nico Jackson stepped out for the Sugarplum Ball in Mayfair on Nov. 20. Supposedly, they are to marry in the spring but there's still no rock on her finger. Gareth Cattermole, Getty Images

Pippa's dress for the ball, a custom creation by Temperley, was black, sheer, intricately embroidered and sparkly. She paired it with a sequined cropped jacket, chandelier earrings, and a chic updo. Now that she's turned 30 smack in the public eye, Pippa's style is maturing. And when she does marry, what kind of dress will she pick? Gareth Cattermole, Getty Images

Pippa pops back up on March 13, 2014, when she attends a memorial service for British broadcaster David Frost at Westminster Abbey. She picks a conservative navy blue button-down coat dress with a tie waist and with matching pumps. She did not arrive with boyfriend Nico, but instead accompanied friends including British adventurer-broadcaster Ben Fogle. Chris Jackson Getty Images

A fervent fan of tennis, Pippa is regularly seen in the royal box at Wimbledon every year. On June 6, she sat behind Michelle Dockery of "Downton Abbey." Pippa was summery in a Carolina Herrera dress in a black-and-white flower pattern, tied at the waist with a black ribbon, and a tailored white blazer over that. Karwai Tang, WireImage

Pippa showed up at the GQ Men of the Year awards at The Royal Opera House on Sept. 2, in London, dressed in an elegant pale pink sequined ankle-length dress with a vintage look by event sponsor Hugo Boss, plus box clutch, strappy sandals and diamond earrings. Mike Marsland, WireImage

Pippa Middleton in the Jackson Hole, Wyo., airport where she went square dancing for a test story for the 'Today' show. Her traveling look: Skinny black jeans, suede booties and a waffle-stitch cardigan by Anthropologie. Photo by Splash News/Corbis

While sister Kate was glamming it up at the Royal Variety Performance on Nov. 13, Pippa was watching tennis: Andy Murray vs Roger Federer at the Barclays ATP World Tour Finals at O2 Arena. Julian Finney/Getty Images

Sure enough, she was wearing the Tabitha Webb dress in the stands at the Queen's Championships in London, Friday, June 19, 2015. Queen's Championship tennis match on Friday, June 19, 2015. Tony O'Brien/REUTERS/Pool

Pippa dressed up for the Boodles Boxing Ball in a bright blue cutout gown by Jenny Packham that showed off toned back and shoulders and a taut torso,on September 12, 2015, in London. Eamonn M. McCormack, Getty Images

Pippa Middleton went to the British Heart Foundation: Roll Out The Red Ball in a Tabitha Webb white shift dress with black piping, and carrying a heart-shaped clutch, in London on Feb. 11. Ian Gavan, Getty Images

Pippa climbs the Rosablanche pass during the Glacier Patrol race near Verbier, Switzerland, on April 20, 2016. Highly-experienced hiker-skiers trek across the Haute Route along the Swiss-Italian border from Zermatt to Verbier. JEAN-CHRISTOPHE BOTT, EPA

Pippa chose a geometric print in pale orange and lavender with an unusual high neck and long sleeves (unusual for the weather) when she took in the tennis at Wimbledon again, on July 4, 2016. Karwai Tang, WireImage